PROJECT SUMMARY Reward-seeking is driven by cues that can have ambiguous predictive and motivational value. To produce adaptive, flexible reward-seeking it is necessary to exploit events surrounding the current encounter with the cue, often called occasion setters, to resolve the ambiguity of Pavlovian reward-paired cues and set the occasion for reward-seeking. For example, an individual who has remained abstinent from drug use for many years may receive routine care in a hospital that provide similar cues for illicit substance use (e.g injections, tourniquets for blood draws) that fail to trigger relapse. However, the sight of an empty syringe or pipe near their home may trigger craving and eventual seeking for drug as the ambiguous cue was encountered in the presence of its occasion setter. The neurobiology underlying occasion setting remains poorly understood. This proposal makes use of a novel model of occasion setting that is robust and amenable to investigations into the psychological and neurobiological factors contributing to occasion setting processes. The basolateral amygdala is a candidate region for the control of occasion setting processes as it is situated to integrate sensory information to modulate the activity of the limbic system. This proposal seeks to elucidate the contributions of the basolateral amygdala to occasion setting by using sophisticated behavioral, electrophysiological, and optogenetic approaches. In aim 1 the contributions of neural activity within the basolateral amygdala to occasion setting will be directly assessed. Electrophysiological recordings of single neurons within the basolateral amygdala will also be conducted to better understand the neural representation of occasion setters. In aim 2 the circuit-level contributions of basolateral amygdala projections throughout the limbic system will be dissected using an optogenetic approach. The long-term goal of this work is to better understand the transformation of reward-predictive stimuli into powerful motivational triggers for relapse and related behaviors. This work will lead to a better understanding of the underlying neural mechanisms of cue- triggered motivation and has the potential to lead to novel therapeutic behavioral and medical interventions.